The present invention relates to a novel insecticidal composition comprising extract(s) obtained from the plant Albizzia lebbeck and xcex4-endotoxin from Bacillus thuringiensis, useful in effectively controlling the lepidopteran crop damages insects. The invention also provides a process for the preparation of the said composition and a method for the application of the composition.
Insecticides have long been used against harmful insects, pests in plants. Insects of the order xe2x80x98Lepidopteraxe2x80x99 particularly cause maximum damage to the field crops, drastically reducing the economic yield of cultivated plants. Globally, the estimates put crop loss due to insect attack somewhere between 18 to 30%. The pesticides and repellents available in the prior art, however, suffer from various deficiencies. Often, compositions provided are insect repellents and not insecticidal. Furthermore, many compositions are either toxic or generally unpleasant to the human beings and animals. Still others require complicated process to provide active ingredients for efficient protection.
Many synthetic prior art compositions have been proposed as insect repellents, but have later been determined to be unsuitable for safe use by humans, as these are not selective and cause grave concern by damaging the environment. Moreover, the use of repellents is not feasible practically for agricultural use.
Various crude extracts and essential oils from plants, such as Neem extract and compounds from Azadirachta indica, citronella oil obtained from Cymbopogon species, or eucalyptus oil obtained from Eucalyptus species etc., have been reported to be useful in insect pest management but mostly as pest repellents. These also suffer from limited activity, unpleasant odor, inconsistency and unreliable composition. Most of the art for plant based insecticide formulation deals with complex compositions with several ingredients required in heavy dosages. The need of the hour is effective insecticidal composition, which is easier to consistently produce and monitor. In the art there are many examples of production and application of different preparations from Bacillus thuringiensis xcex4-endotoxin for plant protection. but the apprehension is of the resistance development in the insect population due to continuous monotonous exposure of this toxin to the insects. Therefore, the applicants studied the combination of microbial pesticides with botanical insecticidal compounds and found that the formulation consisting of diverse compounds with novel and different modes of action is capable of reducing the risk and probability of simultaneous resistance development.
Accordingly, the applicants have developed a plant based insecticidal composition which when combined with other biological insecticide(s) including Bacillus thuringiensis xcex4-endotoxin restricts resistance development against the endotoxin. Further, the composition is environmentally safe and economically effective with significantly lower dosage.
The main object of the invention is to provide a novel insecticidal composition comprising alcoholic extract obtained from the plant Albizzia lebbeck together with Bacillus thuringiensis xcex4-endotoxin.
Yet another object of the invention is to provide an insecticidal combination that is effective at very low dosage against plant pests, such as lepidopteran insects.
Another object of the invention is to provide a composition that may be used for these insects as spray.
Still another object is to provide a composition that exhibits synergistic properties and is capable of enhancing the effect of the endotoxin and killing the resistance developed by insects due to sole application of xcex4-endotoxin.
Another object is to provide process for the preparation of the novel insecticidal composition of the invention.
Yet another object of the invention is to provide a method of application of the composition in terms of sequence of repeat treatments effective in controlling insect population below the threshold level of economic damage.
The present invention provides a novel synergistic composition comprising alcoholic extract obtained from the plant Albizzia lebbeck together with Bacillus thuringiensis xcex4-endotoxin acetone powder. The compositions can be sprayed on the infested standing crops. The said composition exhibits potency at very low dosage against lepidopteran insects. The invention also describes a method for the preparation and application of the insecticidal composition.
The composition and the method of application as described in the present invention is intended to be used against all plant pests, which succumb to the lethal properties of the two biocontrol agents and their synergistic combination thereof.
The invention provides novel insecticidal composition comprising alcoholic extract obtained from the plant Albizzia lebbeck together with Bacillus thuringiensis xcex4-endotoxin useful in controlling insects of the class lepidoptara.
In an embodiment the composition is useful in controlling insects selected from the class lepidoptara comprising Spilarctia obliqua, Spodoptera litura and Heliothis armigera. 
Yet another embodiment the concentration of the plant extract in the composition is about 2.5 mg/ml alcohol for killing insects.
In another embodiment the xcex4-endotoxin obtained from Bacillus thirungiensis is obtained as acetone powder.
In still another embodiment the alcoholic extract is used in combination with Bacillus thuringiensis xcex4-endotoxin at a concentration of about LC 5 or more of both the constituents.
One more embodiment relates to a process for the preparation of the insecticidal composition, said process comprising the steps of collecting, drying, pulverizing part of the plant Albizzia lebbeck, treating the pulverized plant parts with alcohol, filtering and evaporating the alcohol, drying in a freeze drier, and dispersing the alcoholic extract in Bacillus thuringiensis xcex4-endotoxin acetone powder.
In an embodiment the plant parts used for preparation of extract are selected from stem, leaves or seeds.
Yet another embodiment the alcohol is selected from Ethanol, Methanol and Isopropanol.
Still another embodiment the pulverized plant parts are kept in about 100 ml to 5 litre alcohol per 100 gram of plant material overnight for 7 days at room temperature.
In an embodiment the alcohol is filtered out using Whatman no.1 filter paper and evaporated naturally or in a rotavapour at 40-60xc2x0 C.
Yet another embodiment the extract is dried in a freeze drier at xe2x88x92110xc2x0 C.
Still another embodiment the insecticidal composition is capable of controlling in insects selected from the class Lepidoptera comprising Spilarctia obliqua, Spodoptera litura and Heliothis armigera. 
In an embodiment the concentration of the plant extract is about 2.5 mg/ml and the concentration of xcex4-endotoxin is about LC 5 or more of both the constituents.
One more embodiment a method of application of the insecticidal composition said method comprising the step of spraying the insecticidal composition on standing crops.